Transformer apparatus



' 1919460 0. P. BOUQHER 2,391,774

TRANSFORMER APPARATUS Original Filed Dec. 15, 1939 y zla Z;

[VVEA/TO/P .EBaac/zer H15 flrrazavsv Patented Jan. 1, 1946 TRANSFORMER APPARATUS Charles Philippe Boucher, Paterson, N. J., assignor, by mesne assignments, to National Inventions Corporation, a corporation of New Jersey Original application December 13,1939, Serial No. 309,094. Divided and this application February 26, 1942, Serial No. 432,506

1 Claim. ((31. 171119) My application for U. S. Letters Patient is a division of my copending application,'Serial No. 309,094, filed December 13, 1939, and entitled Fluorescent tube system and apparatus, now

tain features of my invention, it may be noted that in the use of fluorescent luminous tubes, as now practiced, the efilciency of light emission per unit of power input is much higher than of Patent 2,289,175 of July 7, 1942, and a continua- 5 incandescent lamps. That is, the brilliancy of tion in part of my copending application, Serial such a tube in lumens, for each watt of power No. 41,476 filed September 30, 1935, and entitled input, is higher. However, the light emitted .rom Electrical transformer apparatus, and the invena single tube is not sufficient to give a satisfaction relates to fluorescent luminous tubes for illutory total-oi light so as to be an adequate submination purposes and more particularly to a w stitute for a single incandescent lamp.

system and apparatus for energizing such tubes. Acco ding y, it is des ab e t oup together One of the objects of my invention is to provide two or more luminous tubes so as to produce a an economical and efiicient source of light which satisfactory total light emission and, furtheris concentrated in a small area and which utimore, it is desirable to have said light emanate lizes inexpensive energizing equipment and apfrom an area small enough that there is a satparatus. isfactory concentration of the light.

Another object is to provide a system and Another purpose for which it is required to transformer apparatus which will operate two or have close gr p o tub s is in cclmect o more luminous tubes in close proximity to give with the use of gas sch e tu e a ng a concentration of light without danger of fiashneo 01 oth ses Whe it s des rable t0 blend aver or 1;- across th t b the difierent colors of two or more tubes.

Another object of my invention is to provide a Numerous arrangements have been designed to I system in which a minimum of high tension cable achieve the desired. concentration oi light .irom connection is necessary and maximum simplicity s disc tubese Oi these arrange= and economy is enjoyed in installation and re 5 ments require costly fixtures and are undesirable placement. from that standpoint. Others are objectionable A further object of my invention is to provide in that the tubes cannot be assembled in close a system which simultaneously operates tubes oi enough p 'fl y o ve th ed Concentraeither equal or unequal resistances from a single tion of light W t t e being p g ex transformer. teriorly across the electrodes of different tubes.

Another object is to provide simple, efficient The light emission per unit area of a fiuores= and inexpensive transformer apparatus for use cent luminous tube varies directly as the amount in the system noted which is readily installed of current flowing through it and inversely as and which is well calculated to serve under the the diameter of the tube. It would therefore many vary n conditions or actual practical use. seem possible to obtain a higher concentration ther objects will in part be apparent and in of light in a given area by increasing the tube part pointed out hereinafter. diameter somewhat and. increasing the density My invention therefore consists in the combioi the current within it. A higher total light nation of elements, features of construction and emission would result with only a slight increase arrangement of parts, as described herein, the 4Q in the area of emission and hence there would scope of the application of which is indicated in be a higher concentration of light. Such an arthe following claim. rangement, however, would require a transformer In the accompanying drawing illustrating cerhaving a core of greater cross-sectional area and min features of my invention: a secondary winding of heavier wire to accom- V Figure 1 i a diagrammatic representation of modate the increased current 108.11. The increase a transformer tube system in which four fiuorin c i s qu b s prohibitive since it escent luminous tubes, each connected to a cors s i w nce with. the sq Of the ur responding secondary coil on the transformer, rent- These Changes n equ p Would mean are placed t their Sides closely adjacent m that the transformer would become prohibitively each other. so expensive;

Figure 2 is a diagrammatic representation of In rder to take advantage of he conomy oi a. similar arrangement except that the tubes are using inexpen iv tr n f rm q p nt nd to of greater length, two such tubes being .illussive a maxim m economy of operation. it is the t g present practice to usefiuorescent luminous tubes As conducive to a clearer understanding of cerof relatively small diameter. Attempts have been made to group two or more of these small diameter tubes closely together in order to produce a satisfactory concentration of light. These attempts have not been successful, however, because large potentialdifferences have existed between adjacent terminals of difierent tubes. As a consequence, the tubes have been short-circuited by exterior spark discharges between their terminals or by a flash-over between tubes somewhere along their lengths. It has thus far been impossible to successfully insulate the tubes from one another so as to fully prevent such sparking.

Accordingly, one object of my invention is to overcome the difiiculty heretofore encountered in the exterior sparking between closely adjacent tubes and provide a tube-transformer system in which economical small diameter tubes and inexpensive transformers are so combined as to give adequately high voltages to operate the tubes and yet the potential diflerence between tubes closely adjacent to each other is too small to cause a spark discharge between them. Referring now more particularly to the practice of my invention, attention is invited to Figure 1 of the drawing in which there is shown a transformer, generally indicated by the number I3. This transformer has a core, preferably of laminated magnetic steel, which comprises two longitudinal bars II and 82 between which T-shaped core pieces I3 and Id of magnetic material are held by core bands It and I3 which are also preferably of magnetic material. The core pieces I3 and I 3 lie in the plane of the bars II and I2 and have inwardly extending legs which are parallel with said bars.

Primary coils PI and P2 are mounted at the centers of core bars I I and I2, respectively. Theyare connected in series at H. n the core section H on either side of primary coil PI are positioned the secondary coils SI and S2, respectively. Likewise, secondary coils S3 and S3 are mounted on core bar I2 on either side of primary coil P2. The secondary coils SI and S2 on the one hand, and S3 and St on the other, are spaced from the primary coils Pi and P2 respectively, to provide room for shunt pieces. The shunt pieces I8 and 2! of magnetic material are mounted on the sides of portion I3aof core .piece I3 and extend toward but short of the bars II and I2, respectively, forming airgaps, of comparatively high magnetic reluctance, GI and G4, with said bars. Similarly shunt pieces I9 and 20 are of magnetic material and are mounted on portion Me of core piece It and form air-gaps G2 and G3 with the bars I I and. I2 of the main core. It will be seen that the core pieces I3, I3a, I8 and 2i generally form the latter H as likewise do the core pieces It, Ila, I3 and 20. Where desired, shunt pieces l3 and 2!, and I9 and 20, may be integral with the respective core pieces I3 and It in order to eliminate the indefinite reluctances of the butt-joints and to largely limit the reluctance of the shunt paths to that of the included air-gaps.

Portions I31: and Ida of core pieces I3 and It may be of larger cross section than shunt pieces I8, I9, 20 and 2I, in order to afford a ready flux by-pass around a secondary coil which is operating under short-circuit conditions and to thus limit the current flow in that coil. Ordinarily, however, portions I31: and I to of the two core pieces need be of only the same sectional areas as the shunt pieces I8, I3, 23 and 2|, as appears more fully below. Core pieces I3 and I 4, however, may be split longitudinally by slots 22 and 23 as shown by dotted lines, each generally H- shaped portion then specifically being in the form of two C-shaped pieces in back-to-back relationship, in which event the total sectional area of each core piece must be double that of each shunt, in order that'the part of the core piece on each side of the slot may accommodate the flux of the associated shunt piece. Each core piece will then operate as two independent shunts. Where the slotted construction is employed, the shunt pieces I8 and 2| on the one hand, and I9 and 20 on the other, preferably are made integral with the associated slotted core pieces I3a and Ida. respectively. In efiect, the shunt construction then would be two cshaped shunt members in a back-to-back relationship.

Shunt pieces i8, I 9, 23 and 2I, may be made movable and mechanically controlled, as described, for example, in my copending application, Serial Number 303,886, so as to change the current output of the transformer.

Like terminals of the secondary coil SI, S2, S3 and S3 are individually grounded to the core by metal strips 23, 25, 23, and 21, respectively, which are held tightly against the core by core bands I5 and I6 above-referred to. Each strip is connected by the inner end of one secondary coil. The core itself is grounded, a at 23.

Each of the other terminals of the secondary coils SI, S2, S3 and S3 is connected to a terminal of one of the luminous tubes TI, T2, T3 and T3 by leads 29, 30, 3i and 32. The other terminals of the tubes are grounded at a single point 33. The core ground 28 may or may not be connected to the tube ground 33 by a conductor 34. This connection is made if either ground 28 or 33 is unreliable.

In the operation of my device, primary coils PI and P2 are energized by a suitable source of alternating current 35, such as a standard singlephase -cycle source of supply at 110 volts,

through leads 33 and 31. The primary coils are so disposed on the core Ill as to work in seriesaiding relation in generating a magnetic flux in the core. 'The flux induces an electromotive 5 one of the tubes TI, T2, T3 or T3 reaches a value great enough to strike an arc across that tube, a current immediately flows through that tube and its secondary coil. Assuming, for example, that an arc has been struck in tube TI,

0 a current will flow through that tube and its secondary coil SI. This current generates a magneto-motive force which opposes the coursing of the main flux through the .core bar II. Consequently, the main flux seeks a path of less reluctance and finds it through core piece I 3, shunt piece I8, air-gap GI, bar I I, core piece It and bar I2. Thereupon, the voltage induced in coil SI will decrease in value, but will still be high enough to energize the tube TI until the electrical potential from source 35 applied across the primary coils PI and P2 decrease in potential in following through its cycle, the tube becomes extinguished.

Thus an excessive flow of current in coil SI and tube TI is prevented. Furthermore, the flux interlinking coil 84 remains substantially undiminished in value. Accordingly, coil S4 is able thereafter to have induced in it a voltage sufficient to strike tube Tl.

Likewise, as arcs are struck across the other tubes T2, T3 and T4, currents flow in their respective secondary coils S2, S3 and S4 and counter magnetomotive forces are generated which divert the main flux across the shunts I9, 20

and 2!, and the corresponding included air-gaps G2, G3 and GE. Thus, if the tube T2, T3 or T4 strikes first, the core flux will be diverted around the corresponding shunt path l9, 2|! or 2| and the included air gap.

When two tubes are lighted together, for instance if tubes Ti and T4. are ignited, the flux path will be through bar i, core piece i4, bar

I2, air-gap G l, shunt piece it, core piece it,

shunt piece it], and air-gap Gt, hack to bar M.

G3, bar l2 and core piece i3 back to bar ll.-

Where the core piece it is slotted at 23, the flux courses longitudinally of the portion Ha to pass around the slot.

When all four tubes Tl, T2, T3 and T4, are illuminated, the flux takes a short path-through bar H, air-gap G2, shunt piece i9, core piece it,

shunt piece 26, air-gap G3, bar i2, air-gap Gt,

shunt piece it, core piece l3, shunt piece It, and air-gap Gl, back to bar I I. Of course, when the core pieces 13 and M are slotted at 22 and 23,

the flux travels around the slot.

When the primary current has alternated to its other hali cycle, the tubes meanwhile having become extinguished, as each tube strikes, the paths of magnetic flux in the core will be the same as those outlined above, except that the flux will course in the opposite direction. Thus, if tube Tl ignites first, the flux will course through bar il, air-gapGL'shunt piece l8, core.

piece [3, bar I2, and core piece ll, back to bar ll. Likewise, when two or more tubes are operating at the same time in the second halfcycle, the flux paths will be same as those outlined above, except that the fiux will be coursing in the opposite direction.

In the event one of the tubes should become short-circuited, as by a film of moisture, packed insect bodies, etc., about the terminals, the operation of the transformer will not be impaired but will be similar to the condition existing where that tube is ignited. Thus, if tube Ti is short-circuited, its secondary coil Si will, from the beginning of the half-cycle of applied potential, commence to develop a strong counter magnetomotive force which will cause the main body of flux to pass around it through core piece It, shunt piece 18 and air-gap GI. Likewise. when any one or, more of the other tubes is short! ed, the main transformer flux will be diverted around the corresponding secondary coilor coils through the shunt pieces and across the air-gaps.

0n the other hand, when one or more of the tubes is open-circuited, as by the breaking of the tube or a substantial reduction in its vacuum. therewinbenonced to divert flux around the secondary coils. Thus, if tube Ti is open-circuited, there is no current flowing through the coil Si and accordingly no counter-magnetomotive force is developed therein. Hence, in opencircuit condition, the flux continues to course the bar ll directly to the bar is without passing through the air-gap GI and the shunt piece I8. Likewise, when any other tube or tubes is shortcircuited, the corresponding secondary coil or coils is not by-passed by the flux, but on the contrary the flux continues to course through that coil or those coils.

I prefer to have primary coils Pi and P2 of the same number of turns in order that the flux generated may be equally distributed through the core legs. I also prefer to have secondary coils Si, S2, S8 and St of the same number of turns in order that the voltages induced in them may be sub-- stantially equal. Of course, if it is desired to use tulzes having difierent striking potentials, sec-- ondary coils of correspondingly difierent voltage ratings may be employed. The objects of my invention are best enjoyed, however, where the coil sections and the tubes are all of like ratings so that the tubes strikesimultaneously and like potential. conditions obtain along their lengths. In this connection, it is to be noted that in the transformer apparatus of my invention primary and secondary coils are symmetrically positioned on the core and with respect to the core shunts employed. The symmetrical construction assures a compact, efficient and balanced unit. Minimum core iron is necessary because uniform flux conditions are maintained. Direct savings therefore are realized in the core construction which incidentally permits savings in the construction of the coils and in the insulating materials used.

Like savings are realized in the casing by virtue of the reduction in size of the transformer unit.

The location of primary and secondary coil in spaced relation assures good heat distribution and dissipation. Moreover, in my transformer, the internally located shunts, that is, shunts internally of the main magnetic path, minimize the extraneous, eifect of the transformer casing or housing, which commonly is formed of iron.

If tubes and coils of different voltage ratings are employed, the corresponding shunt pieces l8, I9, 20, and 2!, are changed in size or they are adjusted to regulate the lengths of the air-gaps GI, G2, G3 and G4. The adjustment is made so that the magnetic reluctance of each shunt path is high if the secondary coil it by-passes has a high voltage rating, ,or low, if the corresponding secondary coil has a low voltage rating. An increase in the reluctance of the shunt path is had through a reduction in the sectional area of the shunt or by increasing the length of the included air-gap. Similarly, the reluctance of the shunt path is decreased by increasing the sectional area of the shunt or by shortening the air-gap.

Inasmuch as the one ends of tube Tl, T2, T3

Considering now another embodiment of my invention, attention is directed to Figure 2, in which I have shown a transformer of the type disclosed in my pending application Serial No. 303,886, entitled Fluorescent tube system and apparatus. The core comprises a laminated bar 38 of magnetic material having abutting legs as and 40, which also abut the cross leg ll A core band 52 may be secured around the main core legs 39 and t and the cross leg 6! to maintain them in fixed relationship. Cross leg ti is H-shaped, having a central part cm and shunt arms bib and die, all of which lie in the plane of the main core. The shunt arms ii lb and c i c extend at right angles to the central part sic and are substantially parallel to the bar 38. These shunt arms form with the legs 39 and 50 air-gaps G! and G2, respectively.

Extending across the extremities of legs 39, d0, air-gaps GI, G2 and shunt arms ilb, die, is a dielectric membrane 03 separating from the core parts the adjustable bridging pieces id and 05. As disclosed in the application above referred to, the purpose of the bridging pieces is to afford a means for adjusting the reluctance of the shunt paths around the air-gaps Gi, G2 respectively, so as to vary the amount of flux which will be bypassed around the secondary coils and'thus vary the voltage and resultant current induced in those coils.

Mounted on the central pan of core bar so is a primary coil P which is energized through leads I36 and it? from a suitable source of alternating current i35 similar to the source 05 of Figure 1.

0n the extremities of core cross leg iii and in symmetrical position with respect to the primary as at MS and the other ends of tubes Ti, T2 are connected together and grounded, as at l 38. The grounds E28, I33 may be connected together by a conductor |3t especially if one of them is unreliable.

The usual high tension cable leads and/or porcelain bushings are employed. between the high tension side of each secondary coil and the corresponding tube electrode. Since one end of each tube is connected to the ground, it follows that the lead at that end need not be a high tension cable. Therefore, instead of requiring two hightension cables and/or bushings per tube as pres ent systems do, by my invention, only one hightension cable and/or bushing is required for each tubte, thus enacting a direct saving in apparatus cos The transformer proper may or may not be enclosed in a container depending upon its location.

For indoor use, this is generally unnecessary. For

outdoor use, however, it usually is necessary. Where an enclosure is desired, the container is filled with insulating compound to prevent the destructive efiects of moisture and ozone on the core and coils.

The tubes Ti, T2 are approximately twice the length of those shown in Figure l and therefore about twice as much potential dirlerence must be impressed across their terminals to strike an arc. The tubes are formed in a iJ-shape and nested one within the other in order to concentrate their light in a small area. To prevent sparking across the opposite teals and to avoid puncture of the tub glass, a space separates the sides oi the opposite legs of the inner tube T2.

As in Figure l, the secondary coils St, S2 of Figure 2 are so connected to the tubes Ti, T2 and to the ground t the le 68, 00 and conseaecaevc ouently the tube terminals to which they are connected are always at a potential in the same direction, either positive or negative, and of nearly the same value at the same instant. Therefore, the maximum possible potential dif ference between the adjacent terminals of tubes Ti, T2 is the differential between the striking voltage of the last tube to strike and the operating voltage of the first tube to strike. Ordinarily, however, this is negligible because the tubes strike about simultaneously and the inductance of the circuit prevents an instantaneous drop in the potential applied. Thus, for all practical purposes. where tubes of the same striking potentials are employed and secondary coils of like turns are used, the potential difierences between the tubes is negligible throughout the various conditions of operation.

As in the construction of Figure l, the transformer of Figure 2 is of a symmetrical form which eilects uniform flux distribution and resultant savings in the size and cost of core iron, coils, insulating materials and casing. efilcient heat distribution and dissipation is obtained.

The manufacturers of glass tubes have found that a tube four feet in length and of 12 millimeters diameter is the most convenient size to maize. A potential of 2000 volts will operate a flourescent luminous tube of this size under any condition of voltage variation encountered in practice; hence that voltage is most practical. In any event, it is not advisable to operate such tubes at a potential higher than 5000 volts. Where the tubes are of the same size and have been carefully pumped, the maximum difierence in their striking potentials has been found to be 200 volts for a 5000-volt circuit. For most practical purposes, this difierence is negligible.

I find that where the distance between electrodes is .095", a potential difference of at least 1900 volts is required to cause a spark discharge between them. There is in my parallel tubes, however, a distance greater than .095" between electrodes. Their centers are .12 millimeters or .47" apart. Gonsequently, a potential in excess of 8000 volts would be required to cause a spark discharge between them. Such a voltage diflerence across like terminals is not encountered in my system.

Where the two tubes are somewhat unequal in striking potentials, I find that after the first tube strikes, there is a large difference in potential between its high voltage terminal and those of the adjacent tubes. Even when operating at a potential of 5000 volts, however, there will not be sumcient potential dinerence to cause sparking across th high voltage terminals. This is true particularly because of my arrangement whereby the voltages impressed on said terminals are of like phase. Moreover, because of the like phase relationships existing, the potential dinesences between the conductive columns of the tubes never become suficient to puncture the tubes. At the zero potential ends of the tubes, they are interconnected and clearly there will be no stress likely to cause sparking.

Since each tube is connected to a separate secondary coil, I find that it is posslble'to simultaneously operate tubes or substantially unequal resistances and st Wtentials, as well: as those orequal resistances. In lllYiSYSfBlfllihQf balcing oi the voltages across or currents through transformer secondary coils is necessary because, by having the te of acent Furthermore,

assume tubes always at potentials corresponding in direction or phase, no difference sufllcient to cause sparking between them is possible.

Although I hav illustrated systems operating four and two tubes in Figures 1 and 2, respectively, it is to be understood that any other number of tubes may be employed. In such systems, it will be understood that each tube is operated by a separate secondary coil, all secondary coils being mounted on a single core energized by a single primary winding.

Thus, it will be seen that there has been provided in my invention a system and apparatus for the illumination of fluorescent tubes in which the various objects hereinbetore set forth, together with many practical advantages, are successfully achieved. It will be seen that the systemis simpl and emcient and that it lends itself to ready installation and ready replacement of tubes. Also that it effectively assures high concentration of light with minimum likelihood of flashover between terminals or rupture of, the tube walls in spite of the high potentials employed and the close physical relationship of the tubes.

Since many .possible embodiments may be made. or my invention and since many changes may be made in the embodiments hereinbefore set forth, it will be understood that all matter described herein, or shown in the drawing, is to be interpreted as illustrative and not in'a limiting sense.

I claim:

Electrical transformer apparatus comprising,

' netic circuit, a primary winding comprising two coil sections one of which is mounted on each linear member near the middle thereof and snugly fitting in the space provided between said substantially H-shaped'core members, two secondary windings each comprising two coil sections mounted on said linear core members with one of said secondary windings snugly fitting in the spaces provided between said linear members and one of said substantially H -shaped members, and the other of said secondary windings snugly fitting in the spaces provided between said linear members and said other substantially H- shaped member, and a pair or clamps maintaining said core in assembled relation, one being about the one adjacent ends of said linear members and the long leg portion of the abutting one substantially H-shaped member and the other being about the other adjacent ends of said linear members and the long leg portion of said abutting other substantially H-shaped member, whereby a compact transformer is had with high operating efllciency.

CHARLES PHILIPPE BOUCHER. 

